1. Field of the Invention
This invention relates to fan control, and more particularly, to controlling the startup routine for a fan.
2. Description of the Related Art
Fan control is an important aspect for cooling modem electronic systems, including computers. Fans are typically used in computers and other electronic systems to evacuate warm air from enclosures in which these systems are contained. This aids in eliminating waste heat which may otherwise build up and adversely affect system operation.
Control of fans in a system typically involves a fan control unit executing a fan control algorithm. A fan control algorithm may determine the method for controlling one or more fans which are configured to evacuate warm air from a system enclosure. The fan control algorithm may include increasing or decreasing the speed of the fan based on a detected temperature. Such control algorithms may also involve turning off a fan if the temperature is deemed cool enough to do so.
If a fan is turned off during the execution of a fan control algorithm, it may need to be restarted if the temperature within the enclosure rises. In order to start the fan, enough power must be applied to the fan to break the inertia of the propeller. Often times, fan control algorithms allow a maximum amount of current to be supplied to a fan in order force the fan blade to rotate at a speed sufficient for effective cooling. However, such a startup routine may cause an undesirable amount of audio noise, and may use an excess of electrical power as well.